When using this action with PHPUnit, the action doesn't produce the expected result. Looking into the code I see, that you only check the first testsuite level of testsuites. But as you can see e.g. here: 1stthomas/ht7-test@3cbe0a7 JUnit reports produced by PHPUnit have 3 or 4 levels.

Thanks to PHPUnit we could just use the first or second testsuite element where the summary of the testcases is added as attribute values, see linked report.

PHPUnit: v11.4
PHP v8.4
test-summary/action v2